Central venous catheters and other catheters inserted through the skin and into the lumen of an artery or vein are widely used in a variety of patients usually in the hospital setting. They provide secure and immediate venous access and allow for the safe administration of fluids and drugs. However, catheter related bloodstream infection (CR-BSI) is a serious and potentially life-threatening complication when catheters and insertion sites become infected with bacterial microorganisms. The insertion sites for these catheters are routinely covered with a dressing as a preventive measure for bacterial infections.
Intravascular catheters are employed routinely in healthcare settings for a number of purposes including infusion of pharmacological drugs and fluids, hemodialysis, monitoring of pressures, and sampling of blood. Although these catheter devices are essential components of modern day medical care, they are also susceptible to microbial contamination. Microbial pathogens can attach to the catheter surface at the site of penetration into the skin. A number of factors renders catheter implants especially susceptible to microbial contamination. Firstly, the catheter essentially compromises the skin's natural protective barrier, providing a direct route to bypass the body's first line of immunity. In addition, upon insertion into the host, the outer surface of the catheter is quickly covered with host proteins that facilitate microbial attachment. There is also evidence that implanted abiotic material itself causes local attenuation of antimicrobial immune responses, thereby providing a fertile breeding ground for microbial biofilm formation. Finally, patients who possess the greatest need for catheterization are often immunologically compromised and are therefore more susceptible to bacterial infection.
Catheters themselves are generally infected via one of two general routes, typically by organisms that compromise the natural flora surrounding the site of catheter insertion. First, microbes may contaminate the catheter along its outer surface, and it is believed that this type of infection often occurs during the initial insertion of the catheter through the skin. Catheters can also be contaminated in their lumenal compartments where fluids flow from contaminated infusate solutions. The most prevalent bacteria found to be the cause of bacterial sepsis from the exterior flora surrounding the insertion site include, but are not limited to, coagulase negative Staphylocci, Staphylococcus epidermitus, Staphylococcus aureus, Escherichia coli, Enterobacter cloacae and Pseudomonas aeruginosa. 
Catheter-related bloodstream infections are notoriously difficult to treat via conventional antibiotic therapy, with associated mortality rates ranging from 12% to 25%. Catheter related bloodstream infection is the most frequent serious complication seen with catheters with infections occurring in as many as 3% to 7% of all catheter placements, which is estimated to be more than 250,000 patients in U.S. hospitals each year. In addition, these infection complications extend hospital stays, necessitate active intervention on the part of healthcare personnel, and result in driving the estimated annual domestic healthcare cost associated with complications arising from these catheter-related infections to more than nine billion dollars.
The presence and growth of harmful and/or potentially harmful bacteria beneath wound dressings or dressings used to cover, indwelling central venous catheters has been shown to cause serious infection, illness, and even death if the bacterial growth goes unnoticed and untreated for even a relatively short period of time. The most prevalent pathogenic bacteria found to be the source of septic infections include, but are not limited to, coagulase negative staphylocci, Staphylococcus epidermitus, Staphalocaccus aureus, Escherichia coli, Enterobacter cloacae, and Pseudommonas aeruginosa. These bacteria can enter the blood stream causing serious and life-threatening illness.
Recent advances in catheter compositions have shown to be relatively successful in preventing some bacterial growth. Some catheters have been coated with antibacterial growth materials, chemicals, and drugs in an effort to prevent infections from entering the bloodstream by way of this conduit. Wound dressings used to cover these catheter insertion sites have similarly been treated with antibacterial agents to inhibit bacterial growth. In most cases the effort has been focused on materials and pharmaceuticals used to prevent bacterial growth. Dressings used to cover indwelling catheters in the hospital setting are also routinely changed and the puncture site carefully examined for bacterial infection. However, an apparatus and method for early warning or indication of the presence of harmful bacterial growth has not been available for use with catheters.
Thus, an apparatus and method for detecting and easily indicating bacterial growth is not presently known but highly desirable.